A Serial Advance Technology Attachment hard drive appears far down in the Basic Input/Output System list because it's attached to a high-numbered port. SATA devices are listed in the BIOS menus according to which ports they are using. A hard drive attached to the SATA1 port will appear in the first position and a hard drive attached to the SATA6 port will appear in the sixth position.

SATA

SATA is a computer peripheral device interface standard used to connect hard drives and optical drives to motherboards. SATA entered the market in 2002 and superseded IDE with faster transfer speeds and easier configuration. SATA assigns each device its own connection port and cable, eliminating the need to designate slave and master assignments on IDE devices that shared a single cable. SATA devices are cross-compatible across hardware generations. For example, a SATA III hard drive will work on a SATA II motherboard. Computers typically have three to six SATA ports, but there are consumer motherboards equipped with anywhere between two and a dozen SATA ports.

Ports are Numbered

The computer designates different SATA ports by number. The device numbers are actually assigned to the ports and not the devices themselves, as an inactive SATA port still has an assigned number. A hard drive that's connected to the lowest number SATA port will show at the top of the list, while a hard drive that's connected to the highest numbered port will show up on the bottom of the list.

BIOS Sort

The BIOS's SATA device listing assignment may not be carried over to the operating system. Some BIOS versions will maintain the SATA device order and number correspondence once loading the operating system, but others sort and reassign device numbers. For example, you may have connected the hard drive to SATA port 0, but there's no guarantee that the hard drive will show up in the top position once you've loaded the operating system. It's easier to identify device order in the operating system based on capacity, partition sizes and model name as opposed to SATA port assignment.

Tiny Text

Motherboards often feature small print on the board itself indicating the port assignment numbers. Each port may have its own text next to it, making it easy to identify. However, ports may be stacked or too closely packed to clearly differentiate number assignment. For example, you may have four ports lined up in a single row clearly labeled "SATA 1," "SATA 2," "SATA 3" and "SATA 4," while you may have two rows of three labeled "SATA 1 - SATA 3" and "SATA 4 - SATA 6" with no clear designation as to which is which.

Recommended Setup

It's a common industry practice to attach the bootable hard drive to the lowest numbered SATA port. However, the SATA port designation has no effect on hard drive performance or prioritization. Ideally, SATA ports should be occupied by devices in ascending order, but if this doesn't work with the system setup, it won't make a difference with system use.

About the Author

Dan Stone started writing professionally in 2006, specializing in education, technology and music. He is a web developer for a communications company and previously worked in television. Stone received a Bachelor of Arts in journalism and a Master of Arts in communication studies from Northern Illinois University.